Eyeglasses generally comprise two lenses and a frame. Examples of frames include, without limitation, those that retain the lenses by holding them in a groove around the perimeter of the lenses, and three-piece frames that include two ear pieces and a nose bridge attached to the lenses (such as shown in prior art FIG. 1).
Whatever the frame style, it is often desirable to change the lenses held by the frame. For example, a wearer's prescription may change, or lenses may become damaged, thus motivating lens changes. Or, different lenses may be suitable for different environments or uses, and a wearer may desire to change out lenses accordingly, while using the same frame. For example, and without limitation, a wearer may desire to change from sunglasses lenses to lenses with a bifocal reader segment, or from lenses with one color tint to another color tint.
Initial coupling of frames and lenses, which is generally performed by eyeglass professionals, is relatively precise work and can be difficult. For example, with three-piece drill-mount frames, the frames are often attached to the lenses by drilling holes in the lenses, and passing shafts from the frames through the holes. In some cases, the shafts are threaded to accommodate a nut for securing the attachment. In other cases, the shafts are pressed into a receiving cap to secure the lens attachment. Whatever the approach, later changing of the lenses is not easily accomplished.
Therefore, a need has arisen for improved methods and apparatus for coupling lenses and frames, and improved eyeglasses.